亚慢性砷暴露对小鼠小脑组织甲状腺激素受体表达的影响

摘要

Objective To determine the influence of subchronic exposure to arsenic ( As) on expression of TR in cerebellum of mouse and to supply basis for mechanism of As -induce neurotoxicity .Methods Forty mice were divided into four groups including three experimental groups (1 mg/L, 2 mg/L and 4 mg/L arsenic trioxide (As2O3)) and one control group.As2O3 was given for consecutive 60 days.Behavioral experiment was used to examine the ability of learning and memory of mouse . Differential expressions of relevant genes of TR were examined with GeneChip technique .Real-time RT-PCR and Western blot were used to detect expressions of TR in gene and protein levels .Results In step-down test , As exposed mice presented more errors and reduced latent period of jumping down from platform .In Gene Chip, expression of TRβin cerebellum was significantly decreased in As exposed groups than that in control group (P<0.05).Compared with control group , expression of TRβmRNA was significantly decreased in As exposed mice by Real -time RT-PCR detection and presented a dose -re-sponse relationship (P<0.05).Compared with control group , expression of TRβ1 protein was decreased in As exposed mice by Western-blot detection and presented a statistical significant decline in 2 mg/L and 4 mg/L As2O3 groups(P<0.05). Conclusion As exposure resulted in reduced ability of learning and memory in mice .The relevant mechanism maybe in that As inhibits expression of TRβ1, which is involved in regulation of long -term memory.%目的：了解砷对小鼠小脑组织甲状腺激素受体（ thyroid hormone receptor ，TR）相关基因和蛋白表达影响，为阐明砷的神经毒作用机制提供靶标依据。方法昆明小鼠40只，按体重随机分为对照组、1 mg/L、2 mg/L和4 mg/L三氧化二砷（ As2 O3）染砷组，每组10只。以自由饮水方式，连续染毒60 d。行为学跳台实验测试砷暴露对小鼠学习记忆能力影响，差异表达基因谱芯片筛查砷暴露小鼠小脑组织TR相关基因的差异表达，Real-time RT-PCR和Western blot技术从基因和蛋白水平进行验证。结果跳台实验中，随砷暴露剂量增加，小鼠发生错误次数增加，从平台跳下的潜伏期缩短，呈剂量-反应关系；基因芯片筛选出砷暴露小鼠小脑组织TRβ基因表达较对照组显著下调（P＜0．05）；Real-time RT-PCR发现，砷暴露小鼠小脑组织TRβmRNA表达显著下降（P＜0．05），且呈剂量-反应关系；Western blot发现，砷暴露小鼠小脑组织TRβ1蛋白表达下降，2 mg/L、4 mg/L剂量染砷组与对照组比较，差异显著（P＜0．05）。结论砷暴露导致小鼠学习记忆功能下降，其机制可能与抑制TR的功能性受体TRβ1表达，进而损伤长时程记忆（ LTM）有关。